The low level of gDNA recovery from clotted blood using
the phenol–chloroform method suggested contamination
of the extracted samples with PCR inhibitors such as phenol
(Nolan et al., 2006), which was supported by the results
of the internal amplification control experiment. Similarly,
a degree of protein contamination (A260:A280 ratio less
than 1.8 (Manchester, 1996)) may also have contributed
to qPCR inhibition, and the subsequent disparity between
the spectrophotometric results and the qPCR results. Thus,
although the spectrophotometer quantification of gDNA is
more convenient it is not an accurate assessment of the
functional quantity of gDNA extracted from clotted blood
using the phenol–chloroform method.